Display of secure messages on a mobile communication device

ABSTRACT

A mobile communications device for the display of an incrementally received message includes a message viewer application for scanning the received portions of the message. On determination that the received portion of the message includes a first displayable portion of the message content, the system signals to a message server to halt the message server from forwarding further portions of the message content. The system provides a mechanism for the user of the mobile communications device to cause the mobile communications device to further signal the the message server to recommence the forwarding of further portions of the secure message content to permit the verification of the e-mail based on the further portions of the secure message content.

This invention relates generally to the display of messages on mobilecommunication devices, and particularly to the display of securemessages on such devices.

Mobile communication devices with display screens are used to receiveand display electronic messages in text or graphical format. It isdesirable for such devices to display received messages, such as e-mailmessages, to users without excessive delay in new information beingdisplayed on the screens of the devices.

However, it is common for electronic messages to include moreinformation than that which will typically be displayed by a mobilecommunication device. For example, an e-mail message as sent may repeatthe body of the message several times in different formats. It is commonfor the same content to be included in plaintext format, in rich textformat and in HTML (hypertext markup language) format. At the mobilecommunication device, it is typically only appropriate to display themessage body in one of the possible formats. Often, for reasons ofefficiency, only the plaintext version of the message body will bedisplayed.

Where a user employs a mobile communications environment in whichmessages are forwarded to the device from a message server, the servermay be configured to send only a single version of the message body tothe mobile communications device. This provides efficiencies in thecommunication to the mobile communication device. From the perspectiveof the user of the device, such an approach will reduce the time thatwould otherwise have been taken for the mobile communications device toreceive, process and redraw the screen as required by the deviceoperation when in receipt of the differently formatted information.

However, this approach may not be available when mobile communicationdevices are configured to receive messages that are sent in accordancewith a secure message format such as the Secure Multipurpose InternetMail Extension (S/MIME) format. For such messages to be verified by amobile communication device, it is often required that the entiremessage (or a significant portion of the message) be received by thedevice. However, where differently formatted message body information isrepeated in the message, the secure message will include more data thanwill be displayed by the mobile communication device. As a result, theuser of the device may experience undesirably slow performance while thedevice carries out processing steps relating to the data that is notdisplayed to the user but which steps are carried out as the devicereceives the information necessary to enable the message to be verifiedby the device.

Accordingly, it is desirable to provide a system and method for thedisplay of secure messages on a mobile communications device in which asecure message may be received and displayed by the device withoutcausing undue delays in message display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of an example communication system in which awireless communication device may be used.

FIG. 2 is a block diagram of a further example communication systemincluding multiple networks and multiple mobile communication devices.

FIG. 3 is a block diagram of a wireless mobile device usable in theexample communication system.

FIG. 4 is a flowchart showing the steps taken by a wireless mobiledevice to communicate with a message server to manage the forwarding ofinformation to the device.

FIG. 5 is a flowchart showing the steps taken by a message server tomanage the forwarding of information that may be encrypted to a wirelessmobile device.

DETAILED DESCRIPTION

Accordingly, a system on a mobile communications device is provided forthe display of an incrementally received secure message. The systemincludes a message viewer application for scanning the received portionsof the message. On determination that the received portion of themessage includes a first displayable portion of the message content, thesystem signals to a message server to halt the message server fromforwarding further portions of the message content. The system furtherprovides a mechanism for the user of the mobile communications device tocause the mobile communications device to further signal the messageserver to recommence the forwarding of further portions of the securemessage content to permit the verification of the e-mail based on thefurther portions of the secure message content.

Advantages include improved display performance for the user of a mobilecommunications device due to the halt in information being received fromthe message server where the mobile device will process, but notdisplay, the information that would otherwise be initially received bythe mobile communications device. However, the user remains able tocarry out a security verification of the received message at the mobilecommunications device.

The invention in one aspect comprises a method for receiving a messageon a mobile communications device, the message comprising a displayablemessage content portion capable of being viewed on the mobilecommunications device, the end of the displayable message contentportion being identified by a predefined indicator, the methodcomprising the steps of: receiving a first segment of the message;scanning the first segment for the predefined indicator; if thepredefined indicator is not found within the first segment,automatically receiving a further segment of the message; and scanningthe further segment of the message for the predefined indicator.

In another aspect, the invention comprises a method for receiving amessage on a mobile communications device, the message comprising adisplayable message content portion capable of being viewed on themobile communications device, the end of the displayable message contentportion being identified by a predefined indicator, the methodcomprising the steps of: receiving a first segment of the message;scanning the first segment for the predefined indicator; if thepredefined indicator is not found within the first segment,automatically receiving a further segment of the message; and scanningthe further segment of the message for the predefined indicator, whereinthe first and any further segment is transmitted to the mobilecommunications device by a server, the method further comprising thestep of automatically transmitting a command to the server to transmit afurther segment of the message, said step of transmitting a commandbeing executable at any time during the method.

In a further aspect, the invention comprises a computer program productcomprising code operative to carry out the steps of any of the aforesaidmethods.

In a further aspect, the invention comprises a system for the display ofa message receivable on a mobile communications device to a user, themessage being automatically incrementally forwarded in segments to themobile communications device by a message server, the message comprisinga message content portion displayable on the mobile communicationsdevice, the system comprising: means adapted to scan received segmentsof the message to determine if the entirety of a first displayableportion of the message has been received by the mobile communicationsdevice; and means adapted to signal the message server to prevent theautomatic incremental forwarding of segments of the message on thedetermination that the entirety of a first displayable portion has beenreceived.

FIG. 1 is an overview of an example communication system in which awireless communication device may be used. One skilled in the art willappreciate that there may be other different topologies, but the systemshown in FIG. 1 helps demonstrate the operation of the secure messageprocessing systems and methods described in the present application.There may also be many message senders and recipients. The simple systemshown in FIG. 1 is for illustrative purposes only.

FIG. 1 shows an e-mail sender 10, the Internet 20, a message serversystem 40, a wireless gateway 85, wireless infrastructure 90, a wirelessnetwork 105 and a mobile communication device 100.

An e-mail sender system 10 may, for example, be connected to an ISP(Internet Service Provider) on which a user of the system 10 has anaccount, located within a company, possibly connected to a local areanetwork (LAN), and connected to the Internet 20, or connected to theInternet 20 through a large ASP (application service provider) such asAmerica Online (AOL). Those skilled in the art will appreciate that thesystems shown in FIG. 1 may instead be connected to a wide area network(WAN) other than the Internet, although e-mail transfers are commonlyaccomplished through Internet-connected arrangements as shown in FIG. 1.

The message server 40 may be implemented, for example, on a networkcomputer within the firewall of a corporation, a computer within an ISPor ASP system or the like, and acts as the main interface for e-mailexchange over the Internet 20. Although other messaging systems mightnot require a message server system 40, a mobile device 100 configuredfor receiving and possibly sending e-mail will normally be associatedwith an account on a message server. Perhaps the two most common messageservers are Microsoft Exchange™ and Lotus Domino™. These products areoften used in conjunction with Internet mail routers that route anddeliver mail. These intermediate components are not shown in FIG. 1, asthey do not directly play a role in the secure message processingdescribed below. Message servers such as server 40 typically extendbeyond just e-mail sending and receiving; they also include dynamicdatabase storage engines that have predefined database formats for datalike calendars, to-do lists, task lists, e-mail and documentation.

The wireless gateway 85 and infrastructure 90 provide a link between theInternet 20 and wireless network 105. The wireless infrastructure 90determines the most likely network for locating a given user and tracksthe user as they roam between countries or networks. A message is thendelivered to the mobile device 100 via wireless transmission, typicallyat a radio frequency (RF), from a base station in the wireless network105 to the mobile device 100. The particular network 105 may bevirtually any wireless network over which messages may be exchanged witha mobile communication device.

As shown in FIG. 1, a composed e-mail message 15 is sent by the e-mailsender 10, located somewhere on the Internet 20. This message 15 isnormally fully in the clear and uses traditional Simple Mail TransferProtocol (SMTP), RFC822 headers and Multipurpose Internet Mail Extension(MIME) body parts to define the format of the mail message. Thesetechniques are known to those skilled in the art. The message 15 arrivesat the message server 40 and is normally stored in a message store. In apreferred embodiment described in further detail below, messagesaddressed to a message server account associated with a host system suchas a home computer or office computer which belongs to the user of amobile device 100 are redirected from the message server 40 to themobile device 100 as they are received.

Regardless of the specific mechanism controlling the forwarding ofmessages to the mobile device 100, the message 15, or possibly atranslated or reformatted version thereof, is sent to the wirelessgateway 85. The wireless infrastructure 90 includes a series ofconnections to wireless network 105. These connections could beIntegrated Services Digital Network (ISDN), Frame Relay or Ticonnections using the TCP/IP protocol used throughout the Internet. Asused herein, the term “wireless network” is intended to include threedifferent types of networks, those being (1) data-centric wirelessnetworks, (2) voice-centric wireless networks and (3) dual-mode networksthat can support both voice and data communications over the samephysical base stations. Combined dual-mode networks include, but are notlimited to, (1) Code Division Multiple Access (CDMA) networks, (2) theGroupe Special Mobile or the Global System for Mobile Communications(GSM) and the General Packet Radio Service (GPRS) networks, and (3)future third-generation (3G) networks like Enhanced Data-rates forGlobal Evolution (EDGE) and Universal Mobile Telecommunications Systems(UMTS). Some older examples of data-centric network include theMobitexTM Radio Network and the DataTACTM Radio Network. Examples ofolder voice-centric data networks include Personal Communication Systems(PCS) networks like GSM, and TDMA systems.

FIG. 2 is a block diagram of a further example communication systemincluding multiple networks and multiple mobile communication devices.The system of FIG. 2 is substantially similar to the FIG. 1 system, butincludes a host system 30, a redirection program 45, a mobile devicecradle 65, a wireless virtual private network (VPN) router 75, anadditional wireless network 110 and multiple mobile communicationdevices 100. As described above in conjunction with FIG. 1, FIG. 2represents an overview of a sample network topology. Although themessage processing systems and methods described herein may be appliedto networks having many different topologies, the network of FIG. 2 isuseful in understanding an automatic e-mail redirection system mentionedbriefly above.

The central host system 30 will typically be a corporate office or otherLAN, but may instead be a home office computer or some other privatesystem where mail messages are being exchanged. Within the host system30 is the message server 40, running on a computer within the firewallof the host system that acts as the main interface for the host systemto exchange e-mail with the Internet 20. In the system of FIG. 2, theredirection program 45 enables redirection of data items from the server40 to a mobile communication device 100. Although the redirectionprogram 45 is shown to reside on the same machine as the message server40 for ease of presentation, there is no requirement that it must resideon the message server. The redirection program 45 and the message server40 are designed to co-operate and interact to allow the pushing ofinformation to mobile devices 100. In this installation, the redirectionprogram 45 takes confidential and non-confidential corporate informationfor a specific user and redirects it out through the corporate firewallto mobile devices 100. A more detailed description of the redirectionsoftware 45 may be found in the commonly assigned U.S. Pat. No.6,219,694 (“the '694 Patent”), entitled “System and Method for PushingInformation From A Host System To A Mobile Data Communication DeviceHaving A Shared Electronic Address”, and issued to the assignee of theinstant application on Apr. 17, 2001, which is hereby incorporated intothe present application by reference. This push technique may use awireless friendly encoding, compression and encryption technique todeliver all information to a mobile device, thus effectively extendingthe security firewall to include each mobile device 100 associated withthe host system 30.

As shown in FIG. 2, there may be many alternative paths for gettinginformation to the mobile device 100. One method for loading informationonto the mobile device 100 is through a port designated 50, using adevice cradle 65. This method tends to be useful for bulk informationupdates often performed at initialization of a mobile device 100 withthe host system 30 or a computer 35 within the system 30. The other mainmethod for data exchange is over-the-air using wireless networks todeliver the information. As shown in FIG. 2, this may be accomplishedthrough a wireless VPN router 75 or through a traditional Internetconnection 95 to a wireless gateway 85 and a wireless infrastructure 90,as described above. A VPN connection could be established directlythrough a specific wireless network 110 to a mobile device 100. Thepossibility of using a wireless VPN router 75 is contemplated to be usedwith Internet Protocol (IP) Version 6 (IPV6) on IP-based wirelessnetworks. This protocol will provide enough IP addresses to dedicate anIP address to every mobile device 100 and thus make it possible to pushinformation to a mobile device 100 at any time. A principal advantage ofusing this wireless VPN router 75 is that it could be an off-the-shelfVPN component, thus it would not require a separate wireless gateway 85and wireless infrastructure 90 to be used. A VPN connection wouldpreferably be a Transmission Control Protocol (TCP)/IP or User DatagramProtocol (UDP)/IP connection to deliver the messages directly to themobile device 100. If a wireless VPN 75 is not available then a link 95to the Internet 20 is the most common connection mechanism available andhas been described above.

In the automatic redirection system of FIG. 2, a composed e-mail message15 leaving the e-mail sender 10 arrives at the message server 40 and isredirected by the redirection program 45 to the mobile device 100. Asthis redirection takes place the message 15 is re-enveloped, asindicated at 80, and a possibly proprietary compression and encryptionalgorithm can then be applied to the original message 15. In this way,messages being read on the mobile device 100 are no less secure than ifthey were read on a desktop workstation such as 35 within the firewall.All messages exchanged between the redirection program 45 and the mobiledevice 100 preferably use this message repackaging technique. Anothergoal of this outer envelope is to maintain the addressing information ofthe original message except the sender's and the receiver's address.This allows reply messages to reach the appropriate destination, andalso allows the “from” field to reflect the mobile user's desktopaddress. Using the user's e-mail address from the mobile device 100allows the received message to appear as though the message originatedfrom the user's desktop system 35 rather than the mobile device 100.

With reference back to the port 50 and cradle 65 connectivity to themobile device 100, this connection path offers many advantages forenabling one-time data exchange of large items. For those skilled in theart of personal digital assistants (PDAs) and synchronization, the mostcommon data exchanged over this link is Personal Information Management(PIM) data 55. When exchanged for the first time this data tends to belarge in quantity, bulky in nature and requires a large bandwidth to getloaded onto the mobile device 100 where it can be used on the road. Thisserial link may also be used for other purposes, including setting up aprivate security key 111 such as an S/MIME or PGP (Pretty Good Privacydata encryption) specific private key, the Certificate (Cert) of theuser and their Certificate Revocation Lists (CRLs) 60. The private keyis preferably exchanged so that the desktop 35 and mobile device 100share one personality and one method for accessing all mail. The Certand CRLs are normally exchanged over such a link because they representa large amount of the data that is required by the device for S/MIME,PGP and other public key security methods.

S/MIME is a message security protocol that enables end-to-endauthorization and protection of data integrity and privacy from the timethat the originator sends the message until the message recipientdecodes and reads the message. S/MIME allows message senders todigitally sign messages using their digital signature, encrypt messageswith the recipient's public key, or both digitally sign and encrypt themessage.

In the preferred embodiment an S/MIME message may be verified both atmessage server 40 and at mobile device 100, both shown in FIG. 2. For auser of the mobile communications device, verification at mobile device100 provides a higher level of security than relying on the verificationat message server 40. In some cases, however, the verification atmessage server 40 may be sufficient for the user. In mobile device 100,a verification application is executable to determine if some or all ofa received message meets message security protocol requirements. Theverification application executed on the mobile device 100 may decryptthe message received at the mobile device 100, or it may verify adigital signature appended to the message, or it may both decrypt andverify a digital signature, depending on whether the message receivedwas encrypted, signed, or both signed and encrypted, respectively. Ifthe verification application is executed at the message server 40, theverification application may still decrypt, verify the digital signatureof, or both decrypt and verify the digital signature of a messagereceived at the server 40, but the resultant decrypted message thendelivered to the mobile device 100 could thus be subject to tamperingundetected by the user of the mobile device 100 upon receipt of theresultant message.

In some cases, the verification application executable by mobile device100 will be unable to complete the verification process without receiptof the entire message or a significant portion of the message. Forexample, where a portion of a message is digitally signed it is typicalfor the verification of the signature to rely on the content of thatportion of the message. Thus where a portion of the message, perhaps asmuch as the entire message body itself, is encoded or signed in thisway, this portion of the message subject to verification, as well as anydigital certificate attached to the message, must be received by mobiledevice 100 before verification at mobile device 100 is able to becarried out. If the message to be verified comprises other fileattachments, then typically all of the attachments must be received bythe mobile device 100 before the verification application can verify themessage.

The above operational characteristic may adversely affect the speed atwhich information is displayed to a user of mobile device 100. This isparticularly the case where the message being received by mobile device100 has either repeated message body contents (as where plaintext, richtext and/or HTML formatted message body versions are included) orattachments. In either case, information may be received whichinformation is not displayable to the user or is not intended to bedisplayed to the user of the mobile device 100.

An approach to solving this potential adverse impact on perceived deviceresponsiveness is for the message server 40 to edit messages beingforwarded to the mobile communication device 100. Such an editing stepcan remove certain repeated portions of the message body. For example,if the message received at the message server 40 contains the content ofthe message in plaintext and in HTML, then the server 40 could strip outthe HTML portion of the message before forwarding it to the mobiledevice 100. However, where the mobile communication device 100 executesa verification application, it will not be possible for the messageserver 40 itself to automatically edit messages to remove such repeatedportions, since this would cause the verification step to fail.

Accordingly, the execution of a verification application by the mobiledevice 100 may require the device 100 to receive non-displayable orrepetitive portions before verification can be accomplished, andconsequently the mobile device 100 may exhibit slower than optimaldisplay characteristics as the non-displayable or repetitive informationis received and processed by mobile device 100.

According to the preferred embodiment, however, a message viewerapplication for displaying messages to a user executable on the mobilecommunication device 100 also operates to potentially reduce the numberof portions of the message that will be forwarded by the message server40. In the preferred embodiment, mobile communication device 100 is ableto communicate with the message server 40 to manage the forwarding ofinformation to the device. As shown in FIG. 4, the message data for afirst message received by the message server 40 is forwarded to themobile communication device 100 in segments or chunks of predeterminedsize (for example, in segments of up to 1 kilobyte), initially with afirst segment being forwarded at step 405. This first segment comprisesonly content that can be displayed to the user on the mobile device 100;so, for example, if the message is encrypted, the segment may be emptyif the message was not previously decrypted by the message server 40. Inthat case, the user would see only header information for the message(e.g., the sender information, the timestamp, or the subject line) andwould be advised by the message viewer application that additionalcontent is available for downloading and verification by theverification application. Otherwise, if the message is not encrypted,the first segment sent at step 405 comprises message content.

After receipt of each segment at the mobile communication device 100,the message viewer application scans the message data received in thatsegment at step 410. There are two results of the segment scan at step410 that are shown in FIG. 4. At decision step 430 ( described below),the renderable nature of the segment determines future steps. Atdecision step 431, the presence of a delimiter determines whether acomplete renderable portion of the message has been received at themobile device 100. For example, if the message viewer application on themobile device 100 is capable of displaying plaintext content to theuser, as opposed to other formats such as Rich Text Format (RTF) orHTML, the message viewer application scans for a predeterminedindicator, such as a defined boundary delimiter, that is known to definethe end of plaintext content. In the preferred embodiment, the messageis defined using the S/MIME protocol and therefore different parts ofthe message body are delimited in defined ways. For example, a plaintextportion of the message body is preceded by a defined boundary delimitersuch as “--Part_Boundary_Alternative” with a content format specifier,for example, “Content-Type: text/plain”. Similar content formatspecifiers (“Content-Type: text/html” and “Content-Type: text/RTF” forHTML and RTF format, respectively) may be found in message contentportions of messages received by the mobile communication device 100.Thus, the message view application at step 410 may scan or search thereceived message segment for the presence of“--Part_Boundary_Alternative Content-Type: text/plain”. If such adelimiter, or other predefined indicator, is found in the messagesegment, then the message view application may determine that it hasreceived a complete portion of plaintext content and instructs theserver 40 to cease sending further segments at step 415. If such adelimiter is not found in the message segment by the scan, then afurther message segment is automatically delivered to the mobilecommunication device 100 by the message server 40 at step 405. Thefurther message segment is similarly scanned or searched at step 410,and yet a further message segment is automatically delivered at step 405from the message server 40 if the delimiter is not found. At any timeduring this process, the user of the mobile communication device 100 mayview the segments of the message that have already been downloaded tothe mobile device 100.

Thus, in the preferred embodiment, the scan carried out by the messageviewer application parses the incoming message segments to determinewhether a first set of plaintext information has been received. Inpreferred embodiment given above, the delimiters are defined inaccordance with Request for Comment 2046 (RFC 2046), which describesMIME alternate encodings of message text. In particular, section 5.1.4of RFC 2046 describes the inclusion of alternative parts in “order ofincreasing faithfulness to the original content”. In practice inaccordance with this order of increasing faithfulness, the most simpleencoding (typically plaintext) is included in the message prior to otherencodings (HTML and Rich Text, for example). Thus, by following themethod outlined above, a complete portion of plaintext content may bedownloaded without user intervention, and without downloading messagesegments comprising exclusively non-displayable or repetitiveinformation to the mobile device 100.

In the preferred embodiment, the automatic delivery of the furthersegments with each repeated execution of step 405 is controlled by acommand referred to here as the AUTO MORE command. Preferably, the AUTOMORE command is specified by the mobile communication device 100 bydefault, although it may be manually specified by the user. When thedefault, or user-specified, AUTO MORE command is invoked, a predefinedindicator, which may be a flag set in a communication from the device tothe server, is sent by the mobile communication device 100 to themessage server 40 at step 395. On receipt of the predefined indicator,the message server 40 will carry out steps to send the further messagesegments to the mobile communication device 100, without furtherrequests being required from the user of the mobile device 100.

Although in FIG. 4 step 395 is shown as being executed prior to step405, persons skilled in the art will appreciate that the step may beexecuted at other points in the process; for example, the predefinedindicator may have already been received by the message server 40 priorto receipt of the message at the server 40 (this may be the case if theAUTO MORE command is invoked by default). Alternatively, step 395 may beexecuted by the mobile communication device 100 after receipt of amessage segment at step 405; for example, the indicator may be sent tothe message server 40 together with other data acknowledging receipt ofthe message segment. Preferably, the predefined indicator iscommunicated to the message server 40 at intervals, or during any otherstatus communication between the mobile communication device 100 and themessage server 40. In the preferred embodiment, the message viewerapplication communicates the predefined indicator to the message server40. In alternate embodiments, a software module on the mobilecommunication device 100 may instead be configured to communicate thepredefined indicator to the message server 40 based on commands sentbetween the message viewer application and the software module.

If the message viewer application on the mobile device 100 detects thepredetermined delimiter in a received message segment, the AUTO MOREcommand for that particular message is disabled, and this iscommunicated to the server 40 at step 415. The message server 40 is thusinstructed to cease sending segments of that message to the mobiledevice 100.

This heuristic is adopted in the preferred embodiment based on theassumption that the viewable content to be received by mobilecommunications device 100 is contained in the first plaintext portion ofthe message content. In fact, other portions of the message may containplaintext portions, or the mobile device may include functionality topermit display of the message content having other encodings. In thepreferred embodiment efficiencies are obtained by using the heuristicdescribed. Preferably, the downloading of further message segments isexecuted by the mobile communication device 100 only when the user isviewing the content downloaded so far of that particular message, inorder to reduce memory usage on the mobile device 100. However, in analternate embodiment, the message viewer application may scan theinitial message segments of other messages not currently being viewed bythe user and download the remaining displayable portions of those othermessages according to the method described above. This embodiment may beless desirable, as it increases the volume of data transmission betweenthe mobile device 100 and the message server 40.

In the preferred embodiment, the potential for perceived delays in theoperation of the mobile device is reduced due to the message server 40halting the automatic forwarding of content to the mobile communicationdevice 100, as described above. Content that is not viewable in thepreferred embodiment by the mobile communication device 100 is notautomatically forwarded to the device by the message server 40. In thesituation where the message comprises signed, encrypted, or signed andencrypted content which is not readily viewable by the message viewerapplication, some efficiencies may still be realized. The message viewerapplication, upon recognition of the message as an encrypted message atstep 430, may disable the AUTO MORE command at step 415. The user maythen optionally manually invoke the AUTO MORE mode in order to downloadand verify the content of the entire message. Preferably, if the messageviewer application recognizes the application as being digitally signedbut not encrypted, the message viewer application still receives afurther segment 405 if the delimiter or other predefined indicator isnot found in the first segment, since the message still containsdisplayable content besides the digital certificate attached to themessage.

Thus, the ability to verify a signed and/or encrypted S/MIME messageremains available to the user of the device 100. In this scenario, themessage viewer application may alternatively provide a VERIFY command tobe manually invoked by the user, which both invokes the AUTO MOREcommand, and then invokes the verification application after allsegments of the signed and/or encrypted message have been downloaded.

It will be appreciated that this approach to the display of securee-mails will require the user to be familiar with the potential for thereceived message to have a tentative security status. A received S/MIMEmessage may be accompanied by an indication that the message server 40has verified the message, but the message may also be indicated to theuser to have an indeterminate status as to verification at the mobiledevice. The user's command to receive further portions of the message(by use of AUTO MORE, for example), if selected, will result in otherparts of the message being forwarded to allow the verification processat the mobile device to be carried out. In the meantime, the userexperience is enhanced as there is a reduction in response time at themobile device 100 due to the reduction in non-viewable information beingforwarded to the device 100.

In a further preferred embodiment, further efficiencies are provided forviewing the displayable portions of a message. Referring to FIG. 5,after the server 40 receives a message for forwarding at step 440,server 40 sends a first segment at step 445. As referred to above,preferably this first segment comprises message content, but in thecircumstance where the message is encrypted, the first segment may notcomprise any message content unless it is decrypted at the server 40.

If the user of mobile communications device 100 wishes to view theremainder of the displayable portion of the message, the user may send aMORE ALL command to the message server 40. This MORE ALL command may beinvoked manually, or it may be set as a default on the mobilecommunication device 100. If the MORE ALL command is not sent to themessage server 40, the steps referred to below will not be carried outby the server of the preferred embodiment. In either case, the mobiledevice 100 transmits a predetermined indicator to the message server 40requesting the remainder of the displayable portion of the message. Oncethe server 40 receives this MORE ALL command (decision branch 450), theserver 40 parses the remainder of the message at step 455 in order toidentify the end of the portion of the message content comprisingcontent that is displayable to the user on the mobile device 100. Thisparsing step is generally similar to the step 410 described in thecontext of the mobile device 100 with respect to each individual segmentreceived at the device 100. However, in this particular embodiment, itis the message server 40 that scans the message for the delimiter orother predefined indicator identifying the end of the displayable (suchas plaintext) portion of the message.

As is described in more detail below, once the complete displayableportion of the message is found by identifying the delimiter within themessage, the message server 40 then transmits the displayable portion ofthe message to the mobile device 100. The transmission of the remainingdisplayable portion of the message may be carried out in a plurality ofsegments, as described above, or the remainder of the displayableportion may be transmitted as a single, larger segment. However theremainder of the displayable portion of the message is received by themobile communication device 100, it is the message server 40 that scansthe message for the appropriate delimiter, and not the mobile device100. The transmission of any further segments of the displayable portionof the message by the server 40 is carried out without any further MOREALL or AUTO MORE commands from the mobile device 100. The MORE ALL andAUTO MORE commands described above may be used concurrently with respectto the same message being viewed on the mobile device 100. While theAUTO MORE command may be invoked by default, and the mobile device 100may scan each received message segment for the predefined indicator ordelimiter indicating the end of the displayable portion of the message,the user may manually intervene and hasten the downloading of the entireviewable content of the message to the mobile device by invoking theMORE ALL command. Preferably, the MORE ALL command is available to beinvoked by the user via a menu option or other command keystroke oraction in the message viewing application.

In the event that the message received by the message server 40 isdigitally signed, encrypted, or both digitally signed and encrypted,some efficiencies may still be realized using the MORE ALL command. Ifthe message is digitally signed (see decision branch 460), then uponreceiving the MORE ALL command from the mobile communication device 100,the message server 40 will have parsed the message to identify thedisplayable content of the message at step 455, but also removes anydigital certificates attached to the message (step 465) beforetransmitting the displayable message content to the mobile device 100 atstep 470. If the message is encrypted (or signed and encrypted)(seedecision branch 475), then the displayable content within the messagemay be transmitted to the mobile device 100 pursuant to a MORE ALLcommand only if the message server 40 receives the session keyapplicable to the encrypted message from the mobile device 100 first.

FIG. 5 shows steps 480, 485 and 490 which carry out the decryption ofthe message, if the session key is available. As will be appreciated theserver 40 will invoke a time out condition if the session key is notreceived.

As will be appreciated by those skilled in the art, this reduces thesecurity of the message and is therefore less desirable. However, if themessage server 40 is provided with the key and can decrypt the message,the message may then be parsed at step 455 and then the displayableportions transmitted to the mobile device 100 at step 470.

As another example, the systems and methods disclosed herein may be usedwith many different computers and devices, such as a wireless mobilecommunications device shown in FIG. 3. With reference to FIG. 3, themobile device 100 is a dual-mode mobile device and includes atransceiver 311, a microprocessor 338, a display 322, non-volatilememory 324, random access memory (RAM) 326, one or more auxiliaryinput/output (I/O) devices 328, a serial port 330, an input device, suchas a keyboard 332, a speaker 334, a microphone 336, a short-rangewireless communications sub-system 340, and other device sub-systems342.

The transceiver 311 includes a receiver 312, a transmitter 314, antennas316 and 318, one or more local oscillators 313, and a digital signalprocessor (DSP) 320. The antennas 316 and 318 may be antenna elements ofa multiple-element antenna, and are preferably embedded antennas.However, the systems and methods described herein are in no wayrestricted to a particular type of antenna, or even to wirelesscommunication devices.

The mobile device 100 is preferably a two-way communication devicehaving voice and data communication capabilities. Thus, for example, themobile device 100 may communicate over a voice network, such as any ofthe analog or digital cellular networks, and may also communicate over adata network. The voice and data networks are depicted in FIG. 3 by thecommunication tower 319. These voice and data networks may be separatecommunication networks using separate infrastructure, such as basestations, network controllers, etc., or they may be integrated into asingle wireless network.

The transceiver 311 is used to communicate with the network 319, andincludes the receiver 312, the transmitter 314, the one or more localoscillators 313 and the DSP 320. The DSP 320 is used to send and receivesignals to and from the transceivers 316 and 318, and also providescontrol information to the receiver 312 and the transmitter 314. If thevoice and data communications occur at a single frequency, orclosely-spaced sets of frequencies, then a single local oscillator 313may be used in conjunction with the receiver 312 and the transmitter314. Alternatively, if different frequencies are utilized for voicecommunications versus data communications for example, then a pluralityof local oscillators 313 can be used to generate a plurality offrequencies corresponding to the voice and data networks 319.Information, which includes both voice and data information, iscommunicated to and from the transceiver 311 via a link between the DSP320 and the microprocessor 338.

The detailed design of the transceiver 311, such as frequency band,component selection, power level, etc., will be dependent upon thecommunication network 319 in which the mobile device 100 is intended tooperate. For example, a mobile device 100 intended to operate in a NorthAmerican market may include a transceiver 311 designed to operate withany of a variety of voice communication networks, such as the Mobitex orDataTAC mobile data communication networks, AMPS, TDMA, CDMA, PCS, etc.,whereas a mobile device 100 intended for use in Europe may be configuredto operate with the GPRS data communication network and the GSM voicecommunication network. Other types of data and voice networks, bothseparate and integrated, may also be utilized with a mobile device 100.

Depending upon the type of network or networks 319, the accessrequirements for the mobile device 100 may also vary. For example, inthe Mobitex and DataTAC data networks, mobile devices are registered onthe network using a unique identification number associated with eachmobile device. In GPRS data networks, however, network access isassociated with a subscriber or user of a mobile device. A GPRS devicetypically requires a subscriber identity module (“SIM”), which isrequired in order to operate a mobile device on a GPRS network. Local ornon-network communication functions (if any) may be operable, withoutthe SIM device, but a mobile device will be unable to carry out anyfunctions involving communications over the data network 319, other thanany legally required operations, such as ‘911’ emergency calling.

After any required network registration or activation procedures havebeen completed, the mobile device 100 may the send and receivecommunication signals, including both voice and data signals, over thenetworks 319. Signals received by the antenna 316 from the communicationnetwork 319 are routed to the receiver 312, which provides for signalamplification, frequency down conversion, filtering, channel selection,etc., and may also provide analog to digital conversion. Analog todigital conversion of the received signal allows more complexcommunication functions, such as digital demodulation and decoding to beperformed using the DSP 320. In a similar manner, signals to betransmitted to the network 319 are processed, including modulation andencoding, for example, by the DSP 320 and are then provided to thetransmitter 314 for digital to analog conversion, frequency upconversion, filtering, amplification and transmission to thecommunication network 319 via the antenna 318.

In addition to processing the communication signals, the DSP 320 alsoprovides for transceiver control. For example, the gain levels appliedto communication signals in the receiver 312 and the transmitter 314 maybe adaptively controlled through automatic gain control algorithmsimplemented in the DSP 320. Other transceiver control algorithms couldalso be implemented in the DSP 320 in order to provide moresophisticated control of the transceiver 311.

The microprocessor 338 preferably manages and controls the overalloperation of the mobile device 100. Many types of microprocessors ormicrocontrollers could be used here, or, alternatively, a single DSP 320could be used to carry out the functions of the microprocessor 338.Low-level communication functions, including at least data and voicecommunications, are performed through the DSP 320 in the transceiver311. Other, high-level communication applications, such as a voicecommunication application 324A, and a data communication application324B may be stored in the non-volatile memory 324 for execution by themicroprocessor 338. For example, the voice communication module 324A mayprovide a high-level user interface operable to transmit and receivevoice calls between the mobile device 100 and a plurality of other voiceor dual-mode devices via the network 319. Similarly, the datacommunication module 324B may provide a high-level user interfaceoperable for sending and receiving data, such as e-mail messages, files,organizer information, short text messages, etc., between the mobiledevice 100 and a plurality of other data devices via the networks 319.The microprocessor 338 also interacts with other device subsystems, suchas the display 322, the RAM 326, the auxiliary input/output (I/O)subsystems 328, the serial port 330, the keyboard 332, the speaker 334,the microphone 336, the short-range communications subsystem 340 and anyother device subsystems generally designated as 342.

Some of the subsystems shown in FIG. 3 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as the keyboard 332 and thedisplay 322 may be used for both communication-related functions, suchas entering a text message for transmission over a data communicationnetwork, and device-resident functions such as a calculator or task listor other PDA type functions.

Operating system software used by the microprocessor 338 is preferablystored in a persistent store such as non-volatile memory 324. Thenon-volatile memory 324 may be implemented, for example, as a Flashmemory component, or as battery backed-up RAM. In addition to theoperating system, which controls low-level functions of the mobiledevice 310, the non-volatile memory 324 includes a plurality of softwaremodules 324A-324N that can be executed by the microprocessor 338 (and/orthe DSP 320), including a voice communication module 324A, a datacommunication module 324B, and a plurality of other operational modules324N for carrying out a plurality of other functions. These modules areexecuted by the microprocessor 338 and provide a high-level interfacebetween a user and the mobile device 100. This interface typicallyincludes a graphical component provided through the display 322, and aninput/output component provided through the auxiliary I/O 328, keyboard332, speaker 334, and microphone 336. The operating system, specificdevice applications or modules, or parts thereof, may be temporarilyloaded into a volatile store, such as RAM 326 for faster operation.Moreover, received communication signals may also be temporarily storedto RAM 326, before permanently writing them to a file system located ina persistent store such as the Flash memory 324.

An exemplary application module 324N that may be loaded onto the mobiledevice 100 is a personal information manager (PIM) application providingPDA functionality, such as calendar events, appointments, and taskitems. This module 324N may also interact with the voice communicationmodule 324A for managing phone calls, voice mails, etc., and may alsointeract with the data communication module for managing e-mailcommunications and other data transmissions. Alternatively, all of thefunctionality of the voice communication module 324A and the datacommunication module 324B may be integrated into the PIM module.

The non-volatile memory 324 preferably also provides a file system tofacilitate storage of PIM data items on the device. The PIM applicationpreferably includes the ability to send and receive data items, eitherby itself, or in conjunction with the voice and data communicationmodules 324A, 324B, via the wireless networks 319. The PIM data itemsare preferably seamlessly integrated, synchronized and updated, via thewireless networks 319, with a corresponding set of data items stored orassociated with a host computer system, thereby creating a mirroredsystem for data items associated with a particular user.

Context objects representing at least partially decoded data items, aswell as fully decoded data items, are preferably stored on the mobiledevice 100 in a volatile and non-persistent store such as the RAM 326.Such information may instead be stored in the non-volatile memory 324,for example, when storage intervals are relatively short, such that theinformation is removed from memory soon after it is stored. However,storage of this information in the RAM 326 or another volatile andnon-persistent store is preferred, in order to ensure that theinformation is erased from memory when the mobile device 100 losespower. This prevents an unauthorized party from obtaining any storeddecoded or partially decoded information by removing a memory chip fromthe mobile device 100, for example.

The mobile device 100 may be manually synchronized with a host system byplacing the device 100 in an interface cradle, which couples the serialport 330 of the mobile device 100 to the serial port of a computersystem or device. The serial port 330 may also be used to enable a userto set preferences through an external device or software application,or to download other application modules 324N for installation. Thiswired download path may be used to load an encryption key onto thedevice, which is a more secure method than exchanging encryptioninformation via the wireless network 319. Interfaces for other wireddownload paths may be provided in the mobile device 100, in addition toor instead of the serial port 330. For example, a USB port would providean interface to a similarly equipped personal computer.

Additional application modules 324N may be loaded onto the mobile device100 through the networks 319, through an auxiliary I/O subsystem 328,through the serial port 330, through the short-range communicationssubsystem 340, or through any other suitable subsystem 342, andinstalled by a user in the non-volatile memory 324 or RAM 326. Suchflexibility in application installation increases the functionality ofthe mobile device 100 and may provide enhanced on-device functions,communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using the mobiledevice 100.

When the mobile device 100 is operating in a data communication mode, areceived signal, such as a text message or a web page download, isprocessed by the transceiver module 311 and provided to themicroprocessor 338, which preferably further processes the receivedsignal in multiple stages as described above, for eventual output to thedisplay 322, or, alternatively, to an auxiliary I/O device 328. A userof mobile device 100 may also compose data items, such as e-mailmessages, using the keyboard 332, which is preferably a completealphanumeric keyboard laid out in the QWERTY style, although otherstyles of complete alphanumeric keyboards such as the known DVORAK stylemay also be used. User input to the mobile device 100 is furtherenhanced with a plurality of auxiliary I/O devices 328, which mayinclude a thumbwheel input device, a touchpad, a variety of switches, arocker input switch, etc. The composed data items input by the user maythen be transmitted over the communication networks 319 via thetransceiver module 311.

When the mobile device 100 is operating in a voice communication mode,the overall operation of the mobile device is substantially similar tothe data mode, except that received signals are preferably be output tothe speaker 334 and voice signals for transmission are generated by amicrophone 336. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on the mobiledevice 100. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 334, the display 322 may alsobe used to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information. Forexample, the microprocessor 338, in conjunction with the voicecommunication module and the operating system software, may detect thecaller identification information of an incoming voice call and displayit on the display 322.

A short-range communications subsystem 340 is also included in themobile device 100. The subsystem 340 may include an infrared device andassociated circuits and components, or a short-range RF communicationmodule such as a Bluetooth™ module or an 802.11 module, for example, toprovide for communication with similarly-enabled systems and devices.Those skilled in the art will appreciate that “Bluetooth” and “802.11”refer to sets of specifications, available from the Institute ofElectrical and Electronics Engineers, relating to wireless personal areanetworks and wireless local area networks, respectively.

The systems' and methods' data may be stored in one or more data stores.The data stores can be of many different types of storage devices andprogramming constructs, such as RAM, ROM, Flash memory, programming datastructures, programming variables, etc. It is noted that data structuresdescribe formats for use in organizing and storing data in databases,programs, memory, or other computer-readable media for use by a computerprogram.

The systems and methods may be provided on many different types ofcomputer-readable media including computer storage mechanisms (e.g.,CD-ROM, diskette, RAM, flash memory, computer's hard drive, etc.) thatcontain instructions for use in execution by a processor to perform themethods' operations and implement the systems described herein.

The computer components, software modules, functions and data structuresdescribed herein may be connected directly or indirectly to each otherin order to allow the flow of data needed for their operations. It isalso noted that a module or processor includes but is not limited to aunit of code that performs a software operation, and can be implementedfor example as a subroutine unit of code, or as a software function unitof code, or as an object (as in an object-oriented paradigm), or as anapplet, or in a computer script language, or as another type of computercode.

Various embodiments of the present invention having been thus describedin detail by way of example, it will be apparent to those skilled in theart that variations and modifications may be made without departing fromthe invention. The invention includes all such variations andmodifications as fall within the scope of the appended claims.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by any one of the patentdocument or patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightswhatsoever.

1. A method for receiving a message on a mobile communications device,the message comprising a displayable message content portion capable ofbeing viewed on the mobile communications device, the end of thedisplayable message content portion being identified by a predefinedindicator, the method comprising the steps of: a) receiving a firstsegment of the message; b) scanning the first segment for the predefinedindicator; c) if the predefined indicator is not found within the firstsegment, automatically receiving a further segment of the message; andd) scanning the further segment of the message for the predefinedindicator.
 2. The method of claim 1, wherein the first and any furthersegment is transmitted to the mobile communications device by a server,the method further comprising the step of automatically transmitting acommand to the server to transmit a further segment of the message, saidstep of transmitting a command being executable at any time during themethod of claim
 1. 3. The method of claim 2, wherein if the step oftransmitting a command has not been executed prior to step d), said stepis not executed at all if the predefined indicator is found within thefirst segment prior to step d).
 4. The method of claim 2, furthercomprising the step of automatically transmitting a command to theserver to halt transmission of any further segments of the message ifthe predefined indicator is found within the first segment.
 5. Themethod of claim 4, wherein the step of transmitting a command to halttransmission is executed prior to step d).
 6. The method of claim 2,further comprising the step of: e) if the predefined indicator is notfound within the further segment, repeatedly receiving other furthersegments of the message and scanning said other further segments for thepredefined indicator, until said predefined indicator is found within afurther segment, wherein each other further segment is scanned prior toreceiving a subsequent further segment.
 7. The method of claim 6,wherein the step of transmitting a command to the server to transmit afurther segment of the message is executed for each iteration of stepe).
 8. The method of claim 7, wherein the step of transmitting a commandto the server to transmit a further segment of the message is notexecuted once the predefined indicator is found within a furthersegment.
 9. The method of claim 8, further comprising the step oftransmitting a command to the server to halt transmission of any furthersegments of the message if the predefined indicator is found within afurther segment.
 10. The method of claim 2 further comprising the stepof receiving, at the server, a message comprising a displayable messagecontent portion.
 11. The method of claim 10 wherein the messagecomprises a displayable message content portion and a non-displayablemessage content portion, such that the displayable message contentportion is located within the message before the non-displayable messagecontent portion.
 12. The method of claim 11 wherein the displayablemessage content portion comprises plaintext.
 13. The method of claim 1further comprising the step of transmitting a command to the server tohalt transmission of any further segments of the message if the messageis determined to be encrypted or signed and encrypted.
 14. The method ofclaim 2 further comprising the step of transmitting a command to theserver to transmit the entirety of the message received by the server tothe mobile communications device, said step being executable at any timeduring the method.
 15. The method of claim 14, further comprising thesteps of receiving the entirety of the message at the mobilecommunications device and verifying the message.
 16. A system for thedisplay of a message receivable on a mobile communications device to auser, the message being automatically incrementally forwarded insegments to the mobile communications device by a message server, themessage comprising a message content portion displayable on the mobilecommunications device, the system comprising: means adapted to scanreceived segments of the message to determine if the entirety of a firstdisplayable portion of the message has been received by the mobilecommunications device; and means adapted to signal the message server toprevent the automatic incremental forwarding of segments of the messageon the determination that the entirety of a first displayable portionhas been received.
 17. The system of claim 16, wherein the segments aresequentially received by the mobile communications device, and whereinthe means adapted to scan received segments of the message to determineif the entirety of a first displayable portion of the message has beenreceived by the mobile communications device are further adapted to scanfor a delimiter within the message denoting the end of the firstdisplayable portion.
 18. The system of claim 16 wherein the meansadapted to signal the message server to prevent the automaticincremental forwarding of segments comprises means to transmit apredefined indicator to the message server.
 19. The system of claim 16further comprising means adapted to permit the user to cause the mobilecommunications device to signal to the message server to forward furtherincremental segments of the message following prevention of theautomatic incremental forwarding of segments of the message.
 20. Acomputer program product comprising code operative to carry out thesteps of the method of claim
 1. 21. A computer program productcomprising code operative to carry out the steps of the method of claim2.
 22. A computer program product comprising code operative to carry outthe steps of the method of claim
 9. 23. A computer program productcomprising code operative to carry out the steps of the method of claim12.